208 
SIR NORMAX LOCKYER AND MR. F. E. BAXAXDALL 
Here we find that of the 29 lines included 12 have a gi’eater intensity in y Cygni, 
11 in the chromosphere, while 6 have been estimated as having ecjiial uitensities in 
the two spectra, thus showing a very evenly-balanced state of affairs. 
Taking the two comparisons together, it would appear that the evidence points to 
the unenhanced lines being, upon the whole, somewhat weakened in the chromo¬ 
sphere at the expense of the enhanced lines. This result tends to show that if anv 
distinction is to lie made between the temperature conditions of the two light sources 
in question, the chromosphere must be placed on a slightly higher level. 
Ihe most marked difference between the spectrum of y Cygni and that of the 
chromosphere occurs in the case of the helium lines. There is no evidence of their 
presence in the former spectrum, while in the latter the stronger helium lines are 
quite conspicuous. We do not, however, know much about the relative positions of 
the helium vapour and the metallic vapours in the chromosphere, and it is quite 
possible that the temperature conditions of the two are vastly different. Another 
notable diffeience between the two sjiectra is in regard to the well-known enhanced 
line of magnesium, X 4481-3. This is fairly prominent in y Cj-gni, but appears to be 
entirely lacking in the chromospheric spectrum. As the enhanced lines of other 
elements are well developed in the chromospheric spectrum, this is a very curious 
1 esult, and difficult to account for, especially as the line in question is well marked in 
iioth y Cygni and a Cygni, iietween which the chromosphere must apparently be 
placed from temperature considerations. 
In the transition from stars resembling the Sun, through y Cygni (Polarian), the 
chromosphere, to a Cygni (Cygnian), the gradual strengthening or weakening of well- 
known groupings of metallic lines can be traced. There cannot be any doubt about 
the authenticity m the spectra of y Cygni and the chromosphere of such groups and 
pairs of metallic lines as the aluminium pair {XX 3944-16, 3961-67), manganese triplet 
(AX 4030-88, 4033-22, 4034-64), iron trqilets (XX 4045-98, 4063-76, 4071-91) and 
(XX 4383-72, 4404-93, 4415-29), chromium triplet (XX 4254-51, 4274-96, 4289-89), and 
the enhanced iron quartette (XX 4508-46, 4515-51, 4520-40, 4522-69). 
Moreover, reference to the Kensington publications of eclipse results,^^ in addition 
to those of Frost,! Evershed,;!; Mitchell,§ and Humpheeys|| will show that there is 
a general consensus of opinion that the chromospheric lines have, upon the whole, 
metallic origins. This is entirely at variance with the conclusion arrived at by 
Professor Dewar, and embodied in his Presidential Address to the British Asso¬ 
ciation, 1902, that the chromospheric lines are to lie accounted for by the lines of 
ki}-pton, xenon, and those of the most volatile atmospheric gases. In tliis connection, 
* ‘Phil. Trans.,’ A, vol. 197, jx 208. 
t ‘ Astrophysical Journal,’ vol. 12, p. 307. 
f ‘ Phil. Trans.,’ A, vol. 197, p. 381. 
§ ‘ Astrophysical Journal,’ vol. 15, jj. 97. 
‘Astrophysical Journal,’ vol. 15, p. 313. 
